High speed keying



Dec. 31, 1935. l l v YQUNG 2,025,797

HIGH SPEED KEYING Filed Feb. 24, 1934 INVE NTOR LLOYD L. YOUNG ATTORNEYPatented Dec. 31, 1935 UNITED STATES PATENT OFFICE HIGH SPEED KEYINGApplication February 24, 1934, Serial No. 712,687

5 Claims.

This invention relates to transmitter keying means and more inparticular to means cooperating with a signal perforated tape or signalmarked tape to convert at high speed the perforations or marks on saidtape into electrical energy, the intensity of which is representative ofthe signal markings or perforations on the tape.

General arrangements known heretofore in the prior are for keying atape, comprise contact members which make and break in accordance withthe markings on the tape. The tape generally includes a continuous rowof uniformly spaced traction or center hole perforations in addition tothe rows of signal perforations on each side of the center row. The tapeis passed over or adjacent to keying members which cooperate with aContact member to complete a circuit through the perforations ormarkings, thereby changing the signal markings or perforations intocharacteristic electrical energy.

In such arrangements considerable difficulty is encountered in providingcontacts light enough to operate at high speed and yet sturdy enough tostand up under the voltages involved in keying the transmitter. Anotherdisadvantage, one which is very serious, is that the speed at which thetape can be keyed is limited by the size and weight of the keyingmembers and the rate at which they can be reversed in motion.

In my U. S. application No. 573,057, filed November 5, 1931, I disclosea high speed keying device which overcomes many disadvantages, includingthose mentioned above, inherent in such keying apparatus. The presentinvention is an improvement over the high speed keying device disclosedin said application.

The object of the present invention is to provide a new and improvedhigh speed keying device in which no electrical contacts through whichcurrent flow are used. Another object of the present invention is toprovide a new and improved high speed keying device in which a minimumnumber of moving parts are used. In this device the only parts whichmove, move through a very small distance.

Briefly the above objects and advantages are attained in accordance withthe present invention by providing a magnetic circuit, the reluctance ofwhich is varied at signal frequency. The circuit is free of contactmaking and braking elements. The keying device which. comprises a wheelhaving a plurality of metal paths on the periphery thereof whichcomplete magnetic circuits during rotation of the wheel, `is sturdy inconstruction, though simple, and is -enclosed within a dustproof casingor cover which supports the incompleted magnetic circuits. The structureoi the wheel and of the casing and associated apparatus is such that itis practically impossible for the same to get out of order. The voltagevariations produced by the successive completion of the magnetic circuitby the armatures controlled by perforations in the tape as the wheelrotates may be utilized in any manner for signalling purposes.Preferably said impulses are used by Way of thermionic relays to actuatea tripping circuit which keys a transmitter.

The novel features of my invention have been pointed out withparticularity in the claims attached hereto. The nature of my inventionand the operation of the same will be better understood from thefollowing detailed description thereof and therefrom when read inconnection with the attached drawing inV which the Figure 1 illustratesa high speed keying device arranged in accordance with my invention andconnected to a thermionic relay which'actuates a tripping circuit topro-duce current impulses of the desired shape and amplitude forsignalling purposes;

While Figure 2 is an end view partly in section of the keying wheel ofFigure l and is for the purpose of showing more clearly certain elementsin the structure of the keying wheel.

Referring to the drawing, M is a ilanged wheel of non-magnetic materialmounted on a shalt H which turns in bearings K, K. The bearings K, K maybe supported in any manner desired. The wheel M carries a plurality ofarmatures C, C of soft magnetic iron of high permeability. The armaturesC are elongated as shown and are spring biased toward the periphery ofthe wheel by means of springs N, N. The ends of the wheel M and thearmatures C carried in the periphery Yof the wheel are covered by coversof non-magnetic material J, J. The covers J, J areV xed on the bearingsK so that they do not rotate with the wheel M. Mounted in the edge orinner portion of each cover J, J is the soft iron core d of anelectro-magnet. Each core d carries a winding d which is connected asshown toa source of alternating current of above audible frequency, say10,000 cycles per second. Around the periphery at the middle of the faceof the wheel M is a plurality of traction pins, a, for

pulling the tape T and aligning the tape with rer spect to the wheel M.The flanges or face of the wheel M are drilled with a multiplicity ofholes to correspond to the signal perforations o r mark-Y ings on thetransmitter tape. One end of the armatures C, C carries a pin, b, whichprotrudes as shown a short distance through the holes in the flanges ofM. Normally the armature C is biased or forced by springs N against theouter periphery of the slots in which they are mounted so that the pins,b, protrude above the outer surface of the wheel. 'Ihe armatures C arepivoted as shown to rockabout the points O, O. The wheel M is built uparound and on the shaft H and a ring integral with the shaft H and iscornposed of non-magnetic parts f, f; e, e, and M for ease ofmanufacture and assembly. The parts are keyed to the shaft by a key y asshown and may be bolted or fastened together by .machine screws notshown. In order to prevent the armatures from tipping and binding,suitable guides are milled in the rings e, ,f as shown more in detail inthe end view at Figure 2 so as to give circumferential or side supportto the armatures. The tape T is passed over the periphery of the wheeland when the wheel rotates either due to a driving force on the shaft Hor to tension on the tape T, the tape is advanced over the wheel enddragging the wheel with it or being pulled by the wheel due to thetraction effect of the pins, a, on the wheel or on the tape.

In setting forthvthe operation of the keying wheel it will first beassumed that the tape has signal perforations or dots. In this casethere will be a perforation for each pin, b, on the armature C and thepins, b, will protrude through the perforations in the tape as the tapeis drawn over the wheel. In other words, under these circumstances,there will be no movements of the armatures since they are normallybiased towards the periphery of the wheel. `Now assume that the tape isentirely blank except for the perforations at the center for drivingpurposes through which pins, a, protrude. Under these circumstances,there will be no perforations for the pins, b, and as the tape passesover thewheel, each pin, b, will be depressed, causing each armature torock about its pivot at O. When the pin is fully depressed by the tapethe outer end of the armature will be raised until the top surface comesin contact, or substantially in contact, with the inner side rim ofcover J. This places the metallic material C close to the pole faces ofthe core, d, which are just flush with the inside surface of the rimcover J. It is now apparent that i when an armature C passes under thepole faces of the electro-magnet, while the armature pin, b, isdepressed by the tape T, the length of the air gap between the polefaces of the core, d, will be reduced to substantially zero. Thereluctance of the magnetic path is now different than it was before thegap was so short.

Now assume that the tape T has normal signal perforations or marksthereon in addition to the traction perforations. Whenever a signalperforation is over the armature C adjacent the core, d, the pin, b,will extend through said perforation and C will not be rocked and willnot shorten the air gap. When a space occurs in the tape, that is nomarking, the pin of the armature C at that instant adjacent the magnet,d, will be depressed by the tape, thus shortening the air gap as thatparticular armature passes under the pole faces of the correspondingmagnet core, d. As one set of perforations on the tape T gives themarking impulses and the other row of perforations or marks gives thespace impulses it is evident thatV when, for instance, the tape has aperforation for one armature pin and not for the next adjacent pin,there will be a change in the reactance in the magneticV windings on thecore, d,

when the air gap is decreased by the absence of the perforation. Thischange in reactance of the circuit produces a change in the voltage dropacross the windings d thereon; This change in voltage may be utilized asexcitation for any 5 signalling purposes. For example, this change involtage may be utilized as excitation for a suitable thermionic tuberelayand telegraphic signal impulses will be sent out when the tape ispassed over the wheel. lo

Suitable provision for the proper biasing of the mark and spacecharacters on the tape may be obtained by the proper position of the twomagnets with respect to each other. The tape may be pulled by an outsidemeans or power l5 may be applied to the shaft H so that the tractionpins, a, on the wheel pull the tape. Suitable end thrust bearings may beprovided in K to permit the wheel M to run true and free and theclearances between the cover J and the 20 wheel M may be so small as toreduce trouble from dust to a minimum. Small size and accessibility,together with the capacity for operation at high speeds without theintroduction of retarding effects of inertia of parts, are obtainable 25because a movement of each armature C can occur only once eachrevolution of the wheel M and the distance of travel of the armature isonly about 51g of an inch and the time of travel is about equal to 1A;revolution of the'wheel. Al- 30 though the wheel might appear fromthedrawing to be large, it may be small or large as desired to meet theparticular requirements. In the drawing it is shown sufficiently largeto clearly illustrate the relation of the parts in- 35 volved.v

The wheel of the present invention has numerous advantages not found inthe high speed keying wheel of my prior application No. 573,057. Forexample, the magnetic circuit is consider- 49 ably shortened. The airgap in the circuit is shortened. The wheel and in particular the movingparts thereof are practically completely enclosed as far as the naturalelements are concerned. This lengthens the operative life of the 45wheel considerably. Moreover, in this wheel no dust can reach the movingparts to clog the same.

The windings d of the vmagnets may be energized in any manner. Forexample, they may 50 be energized by an alternating current source Ilconnected as shown with the windings. The current changes due to changesin the reactance of the windings d which are in turn due to changes inthe reluctance of the magnetic circuits, which changes aretrulycharacteristic of the signal perforations or markings on the tape,may be utllized in any manner for signalling purposes. For example,these voltage changes or current changes may be applied to the terminalsof a co pair of resistances R connected as shown between the controlgrids of a pair of tubes Il). The control grids of these tubes may bemaintained at the desired operating potential by source l2 connected asshown. The anodes of the tubes l0 65 may be connected together by way ofresistances R1 and to a source of potential not shown. Points on theresistances R1 may be connected to a resistance R3 and may be conectedby way of additional resistances I4 to the control grids of "0 a pair oftubes I6 connected in a tripping circuit. The anodes of tubes I6 areconnected together as shown by resistances I 8 and to a source of'potential 20. The anode of each of the tubesV lr6 may be connected byresistance 22 to the 75 control grid of the other tube. This is toproduce a tripping eifect in this circuit. By tripping effect it ismeant that when current starts to flow in the anode circuit of one tubedue to a biasing impulse on the control grid thereof, the drop ofpotential through the resistance I8 in the anode circuit of said tubewill be trans- Initted by way of a resistance 22 to the control grid ofthe other tube to bias the same more negative so that less current willflow in the anode of said other tube. Of course, when less current owsin the anode of the said other tube there is a rise in the potential ofthe resistance I8 in the anode circuit of said tube, which rise istransferred by the resistance 22 to the control grid of the first tubeto make the same more positive. The effect is accumulative so that ifthe control grid of one of the tubes I6 is biased more positive there isan instant switch of the current of the system to the anode circuit ofsaid tube. This switching of current from one tube to the other may beutilized for marking purposes or to key a transmitter. The trippingcircuit described above has been disclosed more in detail in FinchUnited States application No. 364,831, filed May 2l, 1929, andapplication No. 380,447, filed July 23, 1929, and has been claimed insaid applications and per se forms no part of the present invention. Thedescription of the tripping circuit is thought unnecessary at thispoint.

Having thus described my invention and the operation thereof, what Iclaim is:

l. A high speed keying device comprising, a rotatable shaft, anon-magnetic wheel on said shaft, a plurality of armatures pivotallymounted in said wheel and biased toward the periphery thereof, saidarmatures each having a pin normally extending through an opening in theface of said wheel, a tape guide on the periphery of said wheel wherebya perforated or marked tape may be passed over said wheel so that saidpins may extend through the perforations or into the markings in saidtape, and a xed magnet mounted adjacent the periphery of said wheel,said magnet having an air gap adjacent the path of rotation of saidarmatures in the periphery of said wheel.

2. A high speed keying device comprising, a rotatable shaft, anon-magnetic wheel on said shaft, a plurality of armatures pivotallymounted in said wheel, said armatures being spring biased and eachhaving a pin normally extending through an opening in the face of saidwheel, a tape guide on the periphery of said wheel whereby a perforatedtape may be passed over said wheel so that said pins may extend throughthe perforations in said tape, a non-magnetic cover for said wheel, saidcover being non-rotatably mounted relative to said wheel, and a magnetin said cover having an air gap adjacent' the path of rotation of saidarmatures in said wheel.

3. A high speed keying device comprising, a rotatable shaft, anon-magnetic wheel mounted on said shaft for rotation therewith, saidwheel having a plurality of slots in its periphery,'said slots having anopening at one end extending through the periphery of said wheel, anarmature pivotally mountedin each of said slots, said armatures havingan extending portion at one end, springs biasing each of said armaturestoward the outer periphery of said wheel so that said extending portionpasses through said openings in said wheel, a magnetic circuit adjacentthe periphery of said wheel, said magnetic circuit having an air gapadjacent the path of rotation of said armatures in said slots, and atape guide on the periphery of said wheel, said tape having markings orperforations in'which the extending portions on said armatures may passwhen a tape is pulled over said wheel, whereby said armatures arepivoted by the absence of a perforation or marking in said tape to closeor shorten said air gap in said magnet to change the reluctance of saidmagnetic circuit.

4. A high speed keying device comprising, a rotatable shaft, anon-magnetic Wheel mounted on said shaft for rotation therewith,bearings for said shaft at each end of said wheel, said wheel having aplurality of slots in its periphery, each of said slots having anopening at one end extending through the periphery of said wheel, anarmature pivotally mounted in each of said slots, said armatures havingan extending portion at one end, springs biasing each of said armaturestoward the outer periphery of said wheel so that the extending portionsnormally pass through said openings in said wheel, a wheel cover mountedon said bearings and extending over the periphery of said wheel, amagnetic circuit in each of said coverings, said magnetic circuit havingan air gap adjacent the path of rotation of said armatures in saidslots, and a tape guide on the periphery of said wheel, said tape.having markings in which the extending portions on said armatures mayenter when a tape is pulled over said Wheel, whereby said armatures arepivoted by the absence of marking in said tape to close or shorten saidair gap in said magnet to change the reluctance of said magneticcircuit.

5. A high speed keying device comprising, a rotatable shaft, anon-magnetic wheel on said shaft for rotation therewith, a plurality ofarmatures pivotally mounted in recesses in the outer periphery of eachend of said wheel, each armature having a pin normally extending throughan opening in the periphery of said wheel, a tape guide on the peripheryof said wheel, said tape having signal perforations therein throughwhich said pins may pass, a non-magnetic cover mounted on a bearing ateach end of said wheel, said cover extending over said wheel, and amagnetic circuit including an air gap mounted in each of said covers,said air gap vbeing placed adjacent the path of rotation of saidarmatures, whereby vwhen said tape is passed over said Wheel and saidarmatures are rocked on their pivots due to the presence or absence ofsignal perforations in said tape, the air gap is lengthened andshortened. LLOYD L. YOUNG.

